The early stages of visual processing can be divided into modules performing specific functions such as stereopsis, vernier resolution, motion, and texture segregation. To understand these module, it is useful to identify their inputs and outputs. Often, the input/output relationship to two modules can be determined psychophysically. For example, if the output of module A provides input to module B and if B does not influence A, then A probably precedes B. Adaptation to spatial frequency and suppression in binocular rivalry have this sort of sequential relationship. Adaptation can alter rivalry. Rivalry does not influence adaptation. 1) to test the hypothesis that binocular rivalry and stereopsis occupy parallel pathways in human vision 2) to determine if vernier and phase information can be used as input to binocular processes such as rivalry 3) to study the relationship of binocular processing to "pre- attentive" parallel processing 4) to determine if long and short term adaptation have different loci and different functions in human vision 5) to apply these findings to the study of the binocular deficits and spatial distortions in amblyopia.